The traditional wide-field microscope, which is widely used in the fields of biomedical and material science, is difficult to obtain microscopic images of an inner three-dimensional structure of a sample due to its large depth of field. Optical sectioning microscopy, which is a method for obtaining images of an inner three-dimensional structure of a sample, further extends the application scope of microscope. Optical sectioning technology can be divided into fluorescence imaging technology and non-fluorescent imaging technology. At present, optical sectioning technologies using fluorescence imaging, such as scanning confocal fluorescence microscopy, structured light illumination fluorescence microscopy and selective plane illumination fluorescence microscopy, are used most frequently. However, for a non-fluorescent sample, only scattered light of the sample can be used for imaging, which is more difficult to achieve than the optical sectioning technique of fluorescence imaging due to the relatively weak signal-to-noise ratio. The scanning confocal microscopy can also be used to perform optical-section imaging of a non-fluorescent sample. The scanning confocal microscopy uses a conjugate image relationship between an illumination pinhole and a detection pinhole to perform confocal point illumination and point detection imaging, that is, to focus the light emitted from the illumination pinhole on a certain point in the focal plane of the sample, with the light scattered from this point being imaged on the detection pinhole, and any scattered light outside this point being blocked by the detection pinhole. By scanning a sample layer at the focal plane point by point, a higher axial resolution can be obtained than by traditional microscopy, thus realizing optical-section imaging. Obviously, the imaging method of point-by-point scanning is time-consuming and very disadvantageous to image dynamic objects. Therefore, there are limitations to the optical-section imaging of living organisms. The structured light illumination microscopy can also be used to perform optical-section imaging of a non-fluorescent sample, but the illumination device is relatively complex due to the use of structured light illumination. In addition, when using fluorescence imaging, the sample needs to be fluorescently labeled, and the fluorescence labeling may have biotoxicity, thus affecting the sample. The excitation light which excites fluorescence has a short wavelength and may also be phototoxic to the sample.